2. Sample Size

  1. Gerald van Belle

Published Online: 26 SEP 2008

DOI: 10.1002/9780470377963.ch2

Statistical Rules of Thumb, Second Edition

Statistical Rules of Thumb, Second Edition

How to Cite

van Belle, G. (2008) Sample Size, in Statistical Rules of Thumb, Second Edition, John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470377963.ch2

Author Information

  1. University of Washington, Department of Biostatistics and Department of Environmental and Occupational Health Sciences, Seattle, WA

Publication History

  1. Published Online: 26 SEP 2008
  2. Published Print: 18 AUG 2008

ISBN Information

Print ISBN: 9780470144480

Online ISBN: 9780470377963



  • sample size;
  • type 1 error;
  • standard deviation;
  • type 2 error;
  • power


This chapter contains sections titled:

  • Begin with a Basic Formula for Sample Size–Lehr's Equation

  • Calculating Sample Size Using the Coefficient of Variation

  • Ignore the Finite Population Correction in Calculating Sample Size for a Survey

  • The Range of the Observations Provides Bounds for the Standard Deviation

  • Do not Formulate a Study Solely in Terms of Effect Size

  • Overlapping Confidence Intervals do not Imply Nonsignificance

  • Sample Size Calculation for the Poisson Distribution

  • Sample Size Calculation for Poisson Distribution with Background Rate

  • Sample Size Calculation for the Binomial Distribution

  • When Unequal Sample Sizes Matter; When They Don't

  • Determining Sample Size when there are Different Costs Associated with the Two Samples

  • Use the Rule of Threes for 95% Upper Bounds when there Have Been No Events

  • Sample Size Calculations Should be Based on the Way the Data will be Analyzed